The present invention refers to a hub bearing unit intended for mounting of driven or non-driven wheels on vehicles, trailers and similar devices.
Hub bearing units of the above type are earlier known. These bearing units replace shaft and bearing for supporting the vehicle wheels. The units, which incorporate rolling bodies and therefore are to be considered as bearings themselves, are mounted on the vehicle, whereas the wheel is mounted on the rotating part of the units. Units of this type are described i.a. in British Patent Specification No. 1,358,842 and German Pat. No. 3,018,172.
In above British Patent Specification is shown a unit for driven as well as non-driven wheels. The unit comprises two rows of balls which have a common outer race ring with a flange for attachment to the vehicle. This flange, as can be seen, is located non-symmetrically in relation to the rows of balls. This causes problems regarding roundness of the outer race ring at heat treatment thereof and that the stress distribution from the attachment bolts and the stress distribution during operation will be different on the two rows of balls.
The above German Patent in contrast thereto shows a device similar to that described in the British Patent where however the attachment flange on the outer race ring is arranged symmetrically in relation to the rows of balls. A drawback with the device according to this patent is that it is necessary to use moulded steering knuckle housings to which the units are to be mounted. This is of course a drawback from cost aspects. The attachment flange must, as can be seen, be made very high and it is therefore space requiring and expensive to manufacture.
It always has been a desire to be able to use stamped steering knuckle housings for attachment of the hub bearing units. The unit shown in the German Patent cannot be used in connection with such steering knuckle housings as the parts of the housing, which will be located inside the bolts will be too weak. The length of the screws would not be sufficient for a reliable friction joint.